title: Hindlimb unloading in rat decreases preosteoblast proliferation assessed in vivo with BrdU incorporation.
abstract: Immobilization affects bone formation. However, the mechanisms regulating the decrease in osteoblast recruitment remain unclear. The aim of our study was to determine in vivo osteoblastic proliferation after short-term immobilization among the different bone compartments. Twelve Wistar 5-wk-old rats were assigned to two groups: six tail-suspended animals for 6 days and their six age-related controls. Osmotic minipumps, each containing 40 mg of bromodeoxyuridine (BrdU), were implanted intraperitoneally at day 4 until euthanasia. Histomorphometric measurements found a significantly lower bone volume in primary (ISP, -22%) and secondary spongiosa (IISP, -37%) in unloaded rats compared with their age-related controls. BrdU immunohistochemistry showed that the proliferation capacity of osteogenic precursors in ISP (-29%) and preosteoblasts in IISP (-80%) and in periosteum as well as bone marrow cells (-40%) was lowered by unloading. We demonstrated in vivo for the first time that 6-day tail suspension induced a significant decrease in proliferation of periosteal and trabecular preosteoblasts in ISP and IISP as well as in bone marrow cells.
authors.affiliation: Laboratoire de Biologie du Tissu Osseux, Saint-Etienne University, France.
authors.forename: O
authors.initials: O
authors.lastname: Barou
authors.forename: S
authors.initials: S
authors.lastname: Palle
authors.forename: L
authors.initials: L
authors.lastname: Vico
authors.forename: C
authors.initials: C
authors.lastname: Alexandre
authors.forename: M H
authors.initials: MH
authors.lastname: Lafage-Proust
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D001842:Bone and Bones / Q000166:cytology; D001973:Bromodeoxyuridine; D002455:Cell Division; D019417:Hindlimb Suspension / Q000502:physiology*; D008297:Male; D010006:Osteoblasts / Q000166:cytology*; D010012:Osteogenesis / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001973:Bromodeoxyuridine